/*

   Copyright 2001-2003  The Apache Software Foundation 

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */
package org.apache.batik.bridge;

import java.awt.RenderingHints;
import java.awt.geom.Rectangle2D;

import org.apache.batik.gvt.CompositeGraphicsNode;
import org.apache.batik.gvt.GraphicsNode;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.events.MutationEvent;

/**
 * Bridge class for the &lt;g> element.
 *
 * @author <a href="mailto:tkormann@apache.org">Thierry Kormann</a>
 * @version $Id$
 */
public class SVGGElementBridge extends AbstractGraphicsNodeBridge {

    /**
     * Constructs a new bridge for the &lt;g> element.
     */
    public SVGGElementBridge() {}

    /**
     * Returns 'g'.
     */
    public String getLocalName() {
        return SVG_G_TAG;
    }

    /**
     * Returns a new instance of this bridge.
     */
    public Bridge getInstance() {
        return new SVGGElementBridge();
    }

    /**
     * Creates a <tt>GraphicsNode</tt> according to the specified parameters.
     *
     * @param ctx the bridge context to use
     * @param e the element that describes the graphics node to build
     * @return a graphics node that represents the specified element
     */
    public GraphicsNode createGraphicsNode(BridgeContext ctx, Element e) {
        CompositeGraphicsNode gn =
            (CompositeGraphicsNode)super.createGraphicsNode(ctx, e);
	if (gn == null)
	    return null;

        associateSVGContext(ctx, e, gn);

        // 'color-rendering'
        RenderingHints hints = null;
        hints = CSSUtilities.convertColorRendering(e, hints);
        if (hints != null)
            gn.setRenderingHints(hints);

        // 'enable-background'
        Rectangle2D r = CSSUtilities.convertEnableBackground(e);
        if (r != null)
            gn.setBackgroundEnable(r);

        return gn;
    }

    /**
     * Creates a <tt>CompositeGraphicsNode</tt>.
     */
    protected GraphicsNode instantiateGraphicsNode() {
        return new CompositeGraphicsNode();
    }

    /**
     * Returns true as the &lt;g> element is a container.
     */
    public boolean isComposite() {
        return true;
    }

    // BridgeUpdateHandler implementation //////////////////////////////////

    /**
     * Invoked when an MutationEvent of type 'DOMNodeInserted' is fired.
     */
    public void handleDOMNodeInsertedEvent(MutationEvent evt) {
        if ( evt.getTarget() instanceof Element ){
            handleElementAdded((CompositeGraphicsNode)node, 
                               e, 
                               (Element)evt.getTarget());
        }
    }

    /**
     * Invoked when an MutationEvent of type 'DOMNodeInserted' is fired.
     */
    public void handleElementAdded(CompositeGraphicsNode gn, 
                                   Node parent, 
                                   Element childElt) {
        // build the graphics node
        GVTBuilder builder = ctx.getGVTBuilder();
        GraphicsNode childNode = builder.build(ctx, childElt);
        if (childNode == null) {
            return; // the added element is not a graphic element
        }
        
        // Find the index where the GraphicsNode should be added
        int idx = -1;
        for(Node ps = childElt.getPreviousSibling(); ps != null;
            ps = ps.getPreviousSibling()) {
            if (ps.getNodeType() != Node.ELEMENT_NODE)
                continue;
            Element pse = (Element)ps;
            GraphicsNode psgn = ctx.getGraphicsNode(pse);
            while ((psgn != null) && (psgn.getParent() != gn)) {
                // In some cases the GN linked is
                // a child (in particular for images).
                psgn = psgn.getParent();
            }
            if (psgn == null)
                continue;
            idx = gn.indexOf(psgn);
            if (idx == -1)
                continue;
            break;
        }
        // insert after prevSibling, if
        // it was -1 this becomes 0 (first slot)
        idx++; 
        gn.add(idx, childNode);
    }
}
